Part II: Yoreh De'ah

Chapter 29 - THE BAN

A person who deliberately violates a prohibition should be put under a ban
(NIDDUI); a ban is also imposed (after three warnings) on a person who
disobeys a court order (334:1). A ban lasts for seven days (see 334:3)
and may be renewed (see 334:6); if the person still does not repent he is
put in a state of CHEREM (see 334:2,4,7,13,22,27-28,30-31). A rabbi may
impose sanctions (NEZIFAH) on a person who is not respectful to him;
see 334:12,14-16,18-19,21,40-41,45,47. On putting a Torah scholar under
a ban see 334:42. On the imposition and lifting of bans see 334:17,20,
23-26,29,32-339,46; on examples of offenses that require a ban see
334:37-38,43-44; on government pressure to remove a ban see 334:48.

When a person is under a ban everyone but members of his household must
avoid close contact with him; see 334:5 and 377:2. He must not be counted
in any religious quorum and he is forbidden to cut his hair, wash his
clothes, or wear shoes. If he is under a CHEREM he is also forbidden to
teach Torah or to do business, but he is allowed to study Torah and to earn
enough for his needs, and it is permitted to speak to him when necessary
(334:2,11). The court may impose additional restrictions if it wishes
(334:6,8-10).